| 1 | // Copyright 2013 The Go Authors. All rights reserved. |
|---|---|
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package main |
| 6 | |
| 7 | import ( |
| 8 | "fmt" |
| 9 | "go/token" |
| 10 | |
| 11 | "golang.org/x/tools/cmd/guru/serial" |
| 12 | "golang.org/x/tools/go/callgraph" |
| 13 | "golang.org/x/tools/go/callgraph/static" |
| 14 | "golang.org/x/tools/go/loader" |
| 15 | "golang.org/x/tools/go/ssa" |
| 16 | "golang.org/x/tools/go/ssa/ssautil" |
| 17 | ) |
| 18 | |
| 19 | // The callstack function displays an arbitrary path from a root of the callgraph |
| 20 | // to the function at the current position. |
| 21 | // |
| 22 | // The information may be misleading in a context-insensitive |
| 23 | // analysis. e.g. the call path X->Y->Z might be infeasible if Y never |
| 24 | // calls Z when it is called from X. TODO(adonovan): think about UI. |
| 25 | // |
| 26 | // TODO(adonovan): permit user to specify a starting point other than |
| 27 | // the analysis root. |
| 28 | func callstack(q *Query) error { |
| 29 | fset := token.NewFileSet() |
| 30 | lconf := loader.Config{Fset: fset, Build: q.Build} |
| 31 | |
| 32 | if err := setPTAScope(&lconf, q.Scope); err != nil { |
| 33 | return err |
| 34 | } |
| 35 | |
| 36 | // Load/parse/type-check the program. |
| 37 | lprog, err := loadWithSoftErrors(&lconf) |
| 38 | if err != nil { |
| 39 | return err |
| 40 | } |
| 41 | |
| 42 | qpos, err := parseQueryPos(lprog, q.Pos, false) |
| 43 | if err != nil { |
| 44 | return err |
| 45 | } |
| 46 | |
| 47 | prog := ssautil.CreateProgram(lprog, 0) |
| 48 | |
| 49 | ptaConfig, err := setupPTA(prog, lprog, q.PTALog, q.Reflection) |
| 50 | if err != nil { |
| 51 | return err |
| 52 | } |
| 53 | |
| 54 | pkg := prog.Package(qpos.info.Pkg) |
| 55 | if pkg == nil { |
| 56 | return fmt.Errorf("no SSA package") |
| 57 | } |
| 58 | |
| 59 | if !ssa.HasEnclosingFunction(pkg, qpos.path) { |
| 60 | return fmt.Errorf("this position is not inside a function") |
| 61 | } |
| 62 | |
| 63 | // Defer SSA construction till after errors are reported. |
| 64 | prog.Build() |
| 65 | |
| 66 | target := ssa.EnclosingFunction(pkg, qpos.path) |
| 67 | if target == nil { |
| 68 | return fmt.Errorf("no SSA function built for this location (dead code?)") |
| 69 | } |
| 70 | |
| 71 | var callpath []*callgraph.Edge |
| 72 | isEnd := func(n *callgraph.Node) bool { return n.Func == target } |
| 73 | |
| 74 | // First, build a callgraph containing only static call edges, |
| 75 | // and search for an arbitrary path from a root to the target function. |
| 76 | // This is quick, and the user wants a static path if one exists. |
| 77 | cg := static.CallGraph(prog) |
| 78 | cg.DeleteSyntheticNodes() |
| 79 | for _, ep := range entryPoints(ptaConfig.Mains) { |
| 80 | callpath = callgraph.PathSearch(cg.CreateNode(ep), isEnd) |
| 81 | if callpath != nil { |
| 82 | break |
| 83 | } |
| 84 | } |
| 85 | |
| 86 | // No fully static path found. |
| 87 | // Run the pointer analysis and build a complete call graph. |
| 88 | if callpath == nil { |
| 89 | ptaConfig.BuildCallGraph = true |
| 90 | cg := ptrAnalysis(ptaConfig).CallGraph |
| 91 | cg.DeleteSyntheticNodes() |
| 92 | callpath = callgraph.PathSearch(cg.Root, isEnd) |
| 93 | if callpath != nil { |
| 94 | callpath = callpath[1:] // remove synthetic edge from <root> |
| 95 | } |
| 96 | } |
| 97 | |
| 98 | q.Output(fset, &callstackResult{ |
| 99 | qpos: qpos, |
| 100 | target: target, |
| 101 | callpath: callpath, |
| 102 | }) |
| 103 | return nil |
| 104 | } |
| 105 | |
| 106 | type callstackResult struct { |
| 107 | qpos *queryPos |
| 108 | target *ssa.Function |
| 109 | callpath []*callgraph.Edge |
| 110 | } |
| 111 | |
| 112 | func (r *callstackResult) PrintPlain(printf printfFunc) { |
| 113 | if r.callpath != nil { |
| 114 | printf(r.qpos, "Found a call path from root to %s", r.target) |
| 115 | printf(r.target, "%s", r.target) |
| 116 | for i := len(r.callpath) - 1; i >= 0; i-- { |
| 117 | edge := r.callpath[i] |
| 118 | printf(edge, "%s from %s", edge.Description(), edge.Caller.Func) |
| 119 | } |
| 120 | } else { |
| 121 | printf(r.target, "%s is unreachable in this analysis scope", r.target) |
| 122 | } |
| 123 | } |
| 124 | |
| 125 | func (r *callstackResult) JSON(fset *token.FileSet) []byte { |
| 126 | var callers []serial.Caller |
| 127 | for i := len(r.callpath) - 1; i >= 0; i-- { // (innermost first) |
| 128 | edge := r.callpath[i] |
| 129 | callers = append(callers, serial.Caller{ |
| 130 | Pos: fset.Position(edge.Pos()).String(), |
| 131 | Caller: edge.Caller.Func.String(), |
| 132 | Desc: edge.Description(), |
| 133 | }) |
| 134 | } |
| 135 | return toJSON(&serial.CallStack{ |
| 136 | Pos: fset.Position(r.target.Pos()).String(), |
| 137 | Target: r.target.String(), |
| 138 | Callers: callers, |
| 139 | }) |
| 140 | } |
| 141 |
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